1. Technical Field
The present invention relates to a technique for causing an information processing terminal to operate in plural operation modes.
2. Related Art
As a user-friendly interface, a USB (Universal Serial Bus) standard is widely spread. Recently, this USB standard is used in, for example, a portable music player that plays music, a digital camera that photographs and displays images, and an electronic book in which a book converted into text data can be viewed as well. A terminal implemented with such a USB standard (hereinafter referred to as USB terminal) is connected to a host device, whereby new data can be added to the USB terminal from the host device and the USB terminal can transfer data stored therein to the host device. Japanese Patent No. 3766429 discloses a technique for restricting access from a host device to a USB terminal to prevent a malicious user from committing manipulation of data and illegal copying when the USB terminal is lost.
Incidentally, when such a USB terminal is connected to the host device, the USB terminal transitions to a so-called slave mode and is completely controlled by the host device. Therefore, processing corresponding to operation of a user cannot be executed on the USB terminal side. For example, while the portable music player is connected to the host device, addition and deletion of music data can be performed from the host device but music cannot be played on the portable music player side. Therefore, for example, when new music data is added to the portable music player by using the host device, music based on the music data cannot be played on the portable music player side while the portable music player is kept connected to the host device.
In other words, at the time of a reproduction mode when the USB terminal operates alone, the USB terminal manages a file system of a storage device in the USB terminal itself. On the other hand, in the slave mode, the host device at the USB connection destination manages the file system of the storage device in the USB terminal. In order to prevent inconsistency and breakage of data due to conflict, management of the file system of the storage device in the USB terminal can be performed only from one of the USB terminal side and the host device side. The USB terminal in the past performs this switching of the operation modes by judging presence or absence of connection to the host device. Therefore, when the USB terminal is connected to the host device, processing cannot be executed on the USB terminal side. Moreover, in the slave mode, even if the host device and the USB terminal are connected, it is impossible to operate the USB terminal from the host device to cause the USB terminal side to execute processing. This is user-unfriendly and inconvenient.